Rubber crawler

ABSTRACT

The present invention relates to a rubber crawler wherein a core bar having an engaging part at the central position along its length is provided with at least one horizontal projection to each of widthwise side faces of the engaging part at the almost same level as wing portions of the core bar, said horizontal projections projecting in a direction normal to the side faces of the core bar, said core bars are embedded in the crawler main body at equal intervals in a circumferential direction of the crawler so that confronting horizontal projections overlap each other in a widthwise direction of the core bar 1, and tips of the confronting horizontal projections between the embedded core bars are in a three-dimensionally overlapped state in which they overlap each other over a certain length thereof in left and right directions as well as upward and downward directions.

FIELD OF THE INVENTION

The present invention relates to a rubber crawler to be attached to anunder-carriage of a traveling construction machine.

BACKGROUND OF THE INVENTION

Steel caterpillers have usually been attached to the under-carriages oftraveling construction machines, but in recent years rubber crawlershave been applied as well.

FIG. 8 shows a conventional rubber crawler 16 on which an inner flangedinner-flanged idler wheel 19 is rolling. The reference numeral 11 is acore bar. The reference numeral 12, 13 and 14 indicate a wing portion, aprotruding part to prevent disengagements of a wheel, and an engagingpart with a driving wheel, respectively, all of the core bar 11. Thenumeral 17 is a steel cord, 18 is an engaging hole, 19c is a centerrolling part of the idler wheel 19. As shown in this figure, the centerrolling part 19c travels between the protruding parts 13, 13 so thatdisengagements of the wheel can be prevented.

Compared with a steel crawler, the above rubber crawler has thedisadvantage that disengagements of the crawler may easily happen. Thisis mainly because the rubber crawler is partially twisted to therebydisengage from the wheel, when it turns on a stepped ground in theworkshop. FIG. 9 shows a disengagement of the wheel. The crawler isslided sideways between the adjacent core bars 11, 11, and therefore thecenter rolling part 19c of the inner-flanged idler wheel 19 runs on theprotruding part 13, thereby causing the disengagement of the wheel fromthe crawler.

To overcome this problem, increasing the widthwise strength of therubber crawler may be considered.

Then, if the interval of core bars in the rubber crawler is narrowed asthe width thereof is broadened in order to increase the strength of therubber crawler, the widthwise edge portions of each core bar becomeangulate at their turning points, which places the rubber crawler in apolygonal shape. Accordingly, the rubber crawler suffers much bendingfatigue, and therefore its durability decreases.

On the other hand, if a short-pitched rubber crawler (wherein the corebars' interval is half of the conventional rubber crawlet's core barinterval by embedding core bars of narrower width arranged for theinterval) is applied in order to increase the strength, it is excellentin preventing disengagements of the wheel because of the narrowerinterval of the embedded core bars than in a conventional rubbercrawler's, and is excellent in the durability as well. However, this hasnot become a perfect means yet, but still causes disengagements of thecrawler in a large-sized construction machine.

FIGS. 10A and 10B show the core bars 11 vibrating in a circumferentialdirection in the conventional rubber crawler for an inner-flanged wheelfor an inner-flanged wheel. As shown in FIG, 10A, when an outer forcesuch as a load of the wheel is imposed on the top edge portion of theprotruding part 13, the core bar 11 is displaced as shown in a dottedline 13'. Accordingly, the wheel falls between the protruding parts 13and 13 , which causes traveling vibrations of the wheel. As shown inFIG. 10B, when the protruding part 13 is pushed by an ourter force F'from the outside, the core bar 11 is displaced as shown in a dotted line13". Such an outer force F' happens when some stones are pushed into aspace between the protruding parts 13 and 13, or when chassis hook theside upper portion of the protruding part 13 due to disorders of therubber crawler device. In this case, the core bar is pulled out at astroke, or gradually separates from an adherent face with gum to falloff. These vibrations of the core bars are caused by the constructionthat each core bar receives a partial outer force nearly individually.For this solution, providing some effective connecting means between theadjacent core bars is considered.

SUMMARY OF THE INVENTION

Therefore, objects of the present invention are to overcome the aboveproblems, to provide a rubber crawler for an inner-flanged wheel for aninner-flanged wheel which is free from partial slidings of the crawlerand vibrations of the core bar, and to prevent disengagements of thewheel from the crawler as well as to prevent the core bars fromseparating from gum so as to increase the durability.

FIGS. 1˜7 are refered for an easy understanding of the followingdescription. However, it is intended that these figures are illustrativeonly.

First, the present invention is characterized by a rubber crawlerwherein a core bar having an engaging part at the central position alongits length is provided with at least one horizontal projection to eachof widthwise side faces of the engaging part at the almost, same levelas wing portions of the core bar, said horizontal projections projectingin a direction normal to the side faces of the core bar, said core barsare embedded in the crawler main body at equal intervals in acircumferential direction of the crawler so that confronting horizontalprojections overlap each other in a widthwise direction of the core bar,and tips of the confronting horizontal projections between the embeddedcore bars are in a three-dimensionally overlapped state in which theyoverlap each other over a certain length thereof in left and rightdirections as well as upward and downward directions.

As the first embodiment as shown in FIGS. 1˜4, a tip central position ofa horizontal projection of a core bar is caved into a cave s, while atip of a confronting horizontal projection of an adjacent core bar isprovided with a nipple t to enter into said cave s.

As the second embodiment as shown in FIGS. 5˜7, a horizontal projectionof a core bar is formed to be sectionally concave or L-shaped, while aconfronting horizontal projection of an adjacent core bar is formed tobe sectionally convex, L-shaped, or stick-shaped so as to enable athree-dimensionally engaged and overlapped state with each other.

It is preferable that bottom faces of the engaging part of the core barand both ends thereof are thickened to be somewhat lower than the wingportions of the core bar, and that the above-mentioned horizontalprojections are provided to the thickened portions.

Besides as shown in FIG. 7, it is preferable that long slender concavegrooves U or/and U' are provided to either one of or both of a groundingface and a nongrounding face of the rubber crawler at somewhat outerpositions to the side faces of the rubber crawler from the overlappedportion of the horizontal projections between the core bars embedded inthe rubber crawler body, and that said concave grooves U or/and U' arepartially along a circumferential direction of the rubber crawler.

Furthermore, it is preferable that a part of a rubber layer on theoverlapped portion of the horizontal projections between the core barsembedded in the rubber crawler body and its vicinities is partiallyremoved on either one of or both of the grounding face and thenongrounding face so that the overlapped portion of the horizontalprojections is exposed or covered with a thin rubber layer.

In thus constructed rubber crawler, regardless of any outer force toseparate the embedded core bars imposed thereon, the tip portions of theconfronting horizontal projections of the adjacent core bars are incontact with each other over a certain length in three-dimensionaldirections of right, left and upward, downward directions. Accordingly,no disengagements of the wheel from the crawler occur. Besides, becausethe horizontal projections are provided at almost the same level as wingportions of the core bar near a layer of steel cords, there is no bitchange of the overlapped space of the horizontal projections even whenthe rubber crawler is bent to a grounding side or nongrounding side.Especially in the rubber crawler wherein bottom faces of the engagingpart of the core bar and both ends thereof are thickened, the horizontalprojections are provided further close to the layer of steel cords,thereby effecting further small change of the overlapped space thereof.Besides, because the horizontal projections are provided at the almostsame level as wing portions of the core bar near a layer of steel cords,there is no big change of the overlapped space of the horizontalprojections, even when the rubber crawler is bent to a grounding side ornon-grounding side. Especially in the rubber crawler wherein bottomfaces of the engaging part of the core bar and both ends thereof arethickened, the horizontal projections are provided further close to thelayer of steel cords, thereby effecting further small change of theoverlapped space thereof. The rubber crawler shown in FIG. 7 caneffectively prevent cracks, which occur due to long use of the crawler,from growing to steel cord's layer. The rubber crawler wherein a part ofa rubber layer on the overlapped portion of the horizontal projectionsand its vicinities is partially removed can farther prevent the cracksthemselves as much as possible.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 relates to the first embodiment of a core bar for a rubbercrawler according to this invention; FIG. 1A is a front view, FIG. 1B isa back view. FIG. 1C is a left side view, and FIG. 1D is a bottom view.

FIG. 2 is a perspective view of the core bar in FIG. 1.

FIG. 3 shows a rubber crawler where the above core bars are embedded;FIG. 3A is a plane view (on the grounding or the nongrounding side), andFIG. 3B is a sectional view along the line X--X in FIG. 3A.

FIG. 4 shows effects to prevent vibrations of the core bar in the rubbercrawler shown in FIG. 3; FIG. 4A shows a case that an outer force suchas a load of a wheel is imposed on a top end position of a protrudingpart, and FIG. 4B shows a case that an outer force works to push theprotruding part from the outside. FIG. 4C is a perspective view of corebars for the rubber crawler according to the present invention, in whichhorizontal projections are provided at only one end of the engaging parton both sides of the core bars.

FIG. 5 relates to the second embodiment of the core bar for the rubbercrawler according to this invention: FIG. 5A is a perspective view andFIG. 5B is a perspective view of a core bar where the horizontalprojections are arranged differently from those in FIG. 5A.

FIG. 6 relates to the third embodiment of the core bar; FIG. 6A shows arelation of confronting horizontal projections, and FIG. 6B explainseffects to prevent vibrations of the core bar shown in FIG. 6A in therubber crawler.

FIG. 7 shows concave grooves provided to a grounding face and anon-grounding face of the rubber crawler where the above-mentioned corebars are embedded; FIG. 7A is a plane view on the grounding face, FIG.7B is a plane view on the nongrounding face, and FIG. 7C is a sectionalview along the line X--X in FIGS. 7A and 7B.

FIG. 8 relates to a conventional example, showing an engagement of arubber crawler with an inner-flagged idler wheel.

FIG. 9 also relates to the conventional example, showing a disengagementof the rubber crawler from the wheel.

FIGS. 10A and 10B show core bars vibrating in a cirumferential directionin the conventional rubber crawler for the inner-flanged idler wheel.

PREFERRED EMBODIMENTS OF THE PRESENT INVENTION

The first embodiment of this invention is described with reference toFIGS. 1 through 4. The reference numeral 1 is a core bar, 2 is aprotruding part as a track for an inner-flanged wheel, 3 is an engagingpart with a driving wheel, 4 is a wing portion, 5a and 5b are horizontalprojections. As shown in FIG. 1, on one side of the core bar thehorizontal projections 5a, 5a are provided to both ends of the engagingpart 3 whick is provided at the central position along the length of thecore bar, while the horizontal projections 5b, 5b are provided to thesame positions on the other side of the core bar. Said horizontalprojections project in the widthwise direction of the core bar. Thebottom face of the engaging part 3 and both ends thereof is thickened toprovide the horizontal projections 5a, 5b as close as possible to thebottom face. The reference marks s and t are a cave and a nippleprovided to the tips of the horizontal projections 5a, 5b, respectively.The nipple t is inserted into the cave s with a suitable opening. FIG. 2is a perspective view of the core bar shown in FIG. 1, showing arelation of confronting horizontal projections of adjacent core bars.

FIGS. 3A and 3B show a rubber crawler 6 where the above core bars 1 areembedded; FIG. 3A is a plane view (on the nongrounding side), FIG. 3B isa sectional view along the line X--X in FIG. 3A. As shown in FIG. 3A,between adjacent core bars, the nipples t, t of the horizontalprojections 5b, 5b of one core bar are inserted into the caves s, s ofthe horizontal projections 5a, 5a of the next core bar, so that theconfronting horizontal projections can overlap each other over a space dwhen seen from the widthwise and thickness wise directions of thecrawler. The horizontal projections 5a, 5b are provided to both ends ofthe engaging part so that they do not overlap a steel cords' layer 7. Asshown in FIG. 3B, the horizontal projections 5a, 5b are provided asclose as possible to the bottom face. Accordingly, they are embeddednear a steel cords' layer 7, thereby causing no big change in theoverlapped space of the horizontal projections, even if the rubbercrawler bends to the nongrounding side or the grounding side. Thereference numeral 8 is an engaging hole, and R is a lug.

FIGS. 4A and 4B explain effects to prevent vibrations of the core bar inthe rubber crawler 6; FIG. 4A shows a case that an outer force F such asa load of a wheel is imposed on a top end position of a protruding part2, and FIG. 4B shows a case that an outer force F' works to push theprotruding part 2 from the outside. As shown in each figure, since thenipple t of the horizontal projection 5b of one core bar is insertedinto the cave s of the confronting horizontal projections 5a of the nextcore bar, the protruding part 2 is displaced only slightly as describedby a dotted line 2 against the outer force F or F'. Accordingly,vibrations of the core bars 1 are prevented, thereby restrictingcollapses of a wheel between adjacent core bars extremely as well aspreventing the core bars from separating from the rubber crawler. Asshown in FIG. 4C, it is anticipated that the horizontal projections 5a,5b are provided to only one end of the engaging part on both sides ofthe core bar, respectively, and that confronting horizontal projectionsoverlap and engage with each other between adjacent core bars.

FIGS. 5A and 5B relate to the second embodiment of the horizontalprojection. In FIG. 5A, each horizontal projection 5a, 5b, 5c, or 5d hasa sectional shape of either a concave or a convex on its overlappedportion. As shown in this figure, the horizontal projections 5a and 5bof a core bar 1a are sectionally of a concave shape having an opening m,while the horizontal projections 5c and 5d of an adjacent core bar 1a'are of a convex shape having a projection n which is inserted into andengaged with said opening m. The reference marks 5'c and 5'd showsectional shapes of the horizontal projections 5c and 5d on theiroverlapped portions, respectively. FIG. 5B shows that the horizontalprojections 5b and 5d shown in FIG, 5A are exchanged. The referencemarks 5'c and 5'd are sectional shapes of the horizontal projections 5cand 5d on their overlapped portions, respectively. According to theembodiment shown in FIG. 5B wherein the disposition and shape of theright and left horizontal projections are equal on the both sides of thecore bar, rubber crawlers are conveniently produced without any mistakein disposing core bars.

FIGS. 6A and 6B relate to the third embodiment. As shown in FIG. 6A, acore bar is provided with a sectionally L-shaped horizontal projection5a and a stick-shaped horizontal projection 5b on one side of the corebar, and with horizontal projections 5c and 5d of reverse shapes theretoon the other side. Since the proposition and shape of the right and lefthorizontal projections are equal on the both sides of the core bar thisembodiment is also convenient in producing rubber crawlers like theabove case. FIG. 6B explains effects to prevent vibrations of core barsembedded in the rubber crawler 6a. As shown in the figure, thehorizontal projection 5c of a core bar 1b and the horizontal projection5a of a core bar 1b' collide with each other to prevent vibrationsagainst an outer force F, while the horizontal projection 5b of the corebar 1b and the horizontal projection 5d of a core bar 1b" collideagainst an outer force F'.

In FIG. 6B, the reference marks K and K' are flaws on the grounding faceand the nongrounding face of the rubber crawler 6a, respectively.Because of a stage difference on the outer periphery of the horizontalprojections at their overlapped portions, the flaws K concentrate on theouter peripheral rubber of these portions. The flaws K' occur when arubber layer in a minute space between upper and lower horizontalprojections at the overlapped portions is continuously sheared anddamaged. Both flaws K and K' grow in the widthwise and thicknesswisedirections of the rubber crawler to reach the steel cords' layer 7.Consequently, water soaks from the road to corrode and degrade the steelcords thereby decreasing the durability of the rubber crawler.

FIGS. 7A˜7C show a rubber crawler 6a' provided with concave grooves Uand U' for preventing the above problems on the outer periphery and theinner periphery, respectively; FIGS. 7A and 7B are plane views on thegrounding side and the nongrounding side, respectively, and FIG. 7C is asectional view along the line X--X in FIGS. 7A and 7B. As shown in thesefigures, the concave grooves U and U' are provided at somewhat outerpositions to the side faces of the crawler from the overlapped portionsof the horizontal projections 5a, 5c, and the horizontal projections 5b5b on the grounding side and the nongrounding side, respectively.Accordingly, even if the foregoing flaws K occur on the grounding sideof the rubber crawler 6a, they do not reach the steel cords' layer,thereby preventing a decrease of the rubber crawler's durability.

It is intended that shapes of horizontal projections and combinations ofconfronting horizontal projections are not limited to the aboveembodiments, but that any shape and combination are available ifconfronting horizontal projections between embedded core bars areengaged with each other in a three-dimentional direction at theiroverlapped portions.

I claim:
 1. A rubber crawler defining a circumferential direction andcomprising a crawler main body defining a bottom side, and core barseach having a length, a widthwise direction, a central position alongthe length, wing portions, a pair of protruding parts to define a trackfor an inner-flanged wheel, an engaging part at the central position,the engaging part having widthwise side faces, at least one horizontalprojection on each of the widthwise side faces of the engaging part atalmost the same level as the wing portions of the core bar, saidhorizontal projections projecting in a direction normal to the widthwiseside faces of the core bar and confronting horizontal projections ofother core bars, said core bars being embedded in the crawler main bodyat equal intervals in a circumferential direction of the crawler so thatconfronting horizontal projections overlap each other on the bottom sideof the crawler main body in the widthwise direction of the core bars,and the confronting horizontal projections between the embedded corebars having tips in a three-dimensionally overlapped state in which thetips overlap each other over a certain length thereof in left and rightdirections as well as upward and downward directions.
 2. A rubbercrawler according to claim 1, wherein the tips of some of the horizontalprojections of the core bar define recesses and the tips of confrontinghorizontal projections of adjacent core bars define nipples to enterinto the recesses.
 3. A rubber crawler according to claim 2, whereinlong slender concave grooves are provided on at least one of a groundingface and a nongrounding face of the rubber crawler laterally outside theoverlapped portions of the horizontal projections between the core barsembedded in the rubber crawler body, and said concave grooves extendalong portions of the rubber crawler in the circumferential direction.4. A rubber crawler according to claim 3, wherein a rubber layer coversthe overlapped portions of the horizontal projections between the corebars embedded in the rubber crawler body, the rubber layer beingpartially absent on at least one of the grounding face and thenongrounding face at the overlapped portions of the horizontalprojections so that the overlapped portions of the horizontalprojections are exposed.
 5. A rubber crawler according to claim 3,wherein a rubber layer covers the overlapped portions of the horizontalprojections between the core bars embedded in the rubber crawler body,the rubber layer being absent from first portions of at least one of thegrounding face and the nongrounding face at the overlapped portions ofthe horizontal projections, a thinner rubber layer covering said firstportions.
 6. A rubber crawler according to claim 2 wherein a rubberlayer covers the overlapped portions of the horizontal projectionsbetween the core bars embedded in the rubber crawler body, the rubberlayer being absent from first portions of at least one of the groundingface and the nongrounding face at the overlapped portions of thehorizontal projections, a thinner rubber layer covering said firstportions.
 7. A rubber crawler according to claim 2, wherein a rubberlayer covers the overlapped portions of the horizontal projectionsbetween the core bars embedded in the rubber crawler body, the rubberlayer being partially absent on at least one of the grounding face andthe nongrounding face at the overlapped portions of the horizontalprojections so that the overlapped portions of the horizontalprojections are exposed.
 8. A rubber crawler according to claim 2,wherein the engaging part of each core bar is thicker than the wingportions and has a portion extending lower than the wing portions, thehorizontal projections being positioned on the portion of the engagingport extending lower than the wing portions.
 9. A rubber crawleraccording to claim 8, wherein long slender concave grooves are providedon at least one of a grounding face and a nongrounding face of therubber crawler laterally outside the overlapped portions of thehorizontal projections between the core bars embedded in the rubbercrawler body, and said concave grooves extend along portions of therubber crawler in the circumferential direction.
 10. A rubber crawleraccording to claim 9, wherein a rubber layer covers the overlappedportions of the horizontal projections between the core bars embedded inthe rubber crawler body, the rubber layer being partially absent on atleast one of the grounding face and the nongrounding face at theoverlapped portions of the horizontal projections so that the overlappedportions of the horizontal projections are exposed.
 11. A rubber crawleraccording to claim 9 wherein a rubber layer covers the overlappedportions of the horizontal projections between the core bars embedded inthe rubber crawler body, the rubber layer being absent from firstportions of at least one of the grounding face and the nongrounding faceat the overlapped portions of the horizontal projections, a thinnerrubber layer covering said first portions.
 12. A rubber crawleraccording to claim 8, wherein a rubber layer covers the overlappedportions of the horizontal projections between the core bars embedded inthe rubber crawler body, the rubber layer being partially absent on atleast one of the grounding face and the nongrounding face at theoverlapped portions of the horizontal projections so that the overlappedportions of the horizontal projections are exposed.
 13. A rubber crawleraccording to claim 8, wherein a rubber layer covers the overlappedportions of the horizontal projections between the core bars embedded inthe rubber crawler body, the rubber layer being absent from firstportions of at least one of the grounding face and the nongrounding faceat the overlapped portions of the horizontal projections, a thinnerrubber layer covering said first portions.
 14. A rubber crawleraccording to claim 1, wherein long slender concave grooves are providedon at least one of a grounding face and a nongrounding face of therubber crawler laterally outside the overlapped portions of thehorizontal projections between the core bars embedded in the rubbercrawler body, and said concave grooves extend along portions of therubber crawler in the circumferential direction.
 15. A rubber crawleraccording to claim 14, wherein a rubber layer covers the overlappedportions of the horizontal projections between the core bars embedded inthe rubber crawler body, the rubber layer being partially absent on atleast one of the grounding face and the nongrounding face at theoverlapped portions of the horizontal projections so that the overlappedportions of the horizontal projections are exposed.
 16. A rubber crawleraccording to claim 14, wherein a rubber layer covers the overlappedportions of the horizontal projections between the core bars embedded inthe rubber crawler body, the rubber layer being absent from firstportions of at least one of the grounding face and the nongrounding faceat the overlapped portions of the horizontal projections, a thinnerrubber layer covering said first portions.
 17. A rubber crawleraccording to claim 1 wherein a rubber layer covers the overlappedportions of the horizontal projections between the core bars embedded inthe rubber crawler body, the rubber layer being partially absent on atleast one of the grounding face and the nongrounding face at theoverlapped portions of the horizontal projections so that the overlappedportions of the horizontal projections are exposed.
 18. A rubber crawleraccording to claim 1, wherein the tips of some of the horizontalprojections are concave and the tips of the confronting horizontalprojections on adjacent core bars are convex, so as to enable athree-dimensionally overlapped state with each other between theembedded core bars.
 19. A rubber crawler according to claim 18, whereinlong slender concave grooves are provided on at least one of a groundingface and a nongrounding face of the rubber crawler laterally outside theoverlapped portions of the horizontal projections between the core barsembedded in the rubber crawler body, and said concave grooves extendalong portions of the rubber crawler in the circumferential direction.20. A rubber crawler according to claim 19, wherein a rubber layercovers the overlapped portions of the horizontal projections between thecore bars embedded in the rubber crawler body, the rubber layer beingpartially absent on at least one of the grounding face and thenongrounding face at the overlapped portions of the horizontalprojections so that the overlapped portions of the horizontalprojections are exposed.
 21. A rubber crawler according to claim 19,wherein a rubber layer covers the overlapped portions of the horizontalprojections between the core bars embedded in the rubber crawler body,the rubber layer being absent from first portions of at least one of thegrounding face and the nongrounding face at the overlapped portions ofthe horizontal projections, a thinner rubber layer covering said firstportions.
 22. A rubber crawler according to claim 18, wherein theengaging part of each core bar is thicker than the wing portions and hasa portion extending lower than the wing portions, the horizontalprojections being positioned on the portion of the engaging portextending lower than the wing portions.
 23. A rubber crawler accordingto claim 22, wherein a rubber layer covers the overlapped portions ofthe horizontal projections between the core bars embedded in the rubbercrawler body, the rubber layer being absent from first portions of atleast one of the grounding face and the nongrounding face at theoverlapped portions of the horizontal projections, a thinner rubberlayer covering said first portions.
 24. A rubber crawler according toclaim 22, wherein a rubber layer covers the overlapped portions of thehorizontal projections between the core bars embedded in the rubbercrawler body, the rubber layer being partially absent on at least one ofthe grounding face and the nongrounding face at the overlapped portionsof the horizontal projections so that the overlapped portions of thehorizontal projections are exposed.
 25. A rubber crawler according toclaim 22, wherein long slender concave grooves are provided on at leastone of a grounding face and a nongrounding face of the rubber crawlerlaterally outside the overlapped portions of the horizontal projectionsbetween the core bars embedded in the rubber crawler body, and saidconcave grooves extend along portions of the rubber crawler in thecircumferential direction.
 26. A rubber crawler according to claim 25,wherein a rubber layer covers the overlapped portions of the horizontalprojections between the core bars embedded in the rubber crawler body,the rubber layer being partially absent on at least one of the groundingface and the nongrounding face at the overlapped portions of thehorizontal projections so that the overlapped portions of the horizontalprojections are exposed.
 27. A rubber crawler according to claim 25,wherein a rubber layer covers the overlapped portions of the horizontalprojections between the core bars embedded in the rubber crawler body,the rubber layer being absent from first portions of at least one of thegrounding face and the nongrounding face at the overlapped portions ofthe horizontal projections, a thinner rubber layer covering said firstportions.
 28. A rubber crawler according to claim 18, wherein a rubberlayer covers the overlapped portions of the horizontal projectionsbetween the core bars embedded in the rubber crawler body, the rubberlayer being partially absent on at least one of the grounding face andthe nongrounding face at the overlapped portions of the horizontalprojections so that the overlapped portions of the horizontalprojections are exposed.
 29. A rubber crawler according to claim 18,wherein a rubber layer covers the overlapped portions of the horizontalprojections between the core bars embedded in the rubber crawler body,the rubber layer being absent from first portions of at least one of thegrounding face and the nongrounding face at the overlapped portions ofthe horizontal projections, a thinner rubber layer covering said firstportions.
 30. A rubber crawler according to claim 1, wherein some of thehorizontal projections are L-shaped in transverse cross section and theconfronting horizontal projections on adjacent core bars arestick-shaped, so as to enable a three-dimensionally overlapped statewith each other between the embedded core bars.
 31. A rubber crawleraccording to claim 30, wherein long slender concave grooves are providedon at least one of a grounding face and a nongrounding face of therubber crawler laterally outside the overlapped portions of thehorizontal projections between the core bars embedded in the rubbercrawler body, and said concave grooves extend along portions of therubber crawler in the circumferential direction.
 32. A rubber crawleraccording to claim 31, wherein a rubber layer covers the overlappedportions of the horizontal projections between the core bars embedded inthe rubber crawler body, the rubber layer being partially absent on atleast one of the grounding face and the nongrounding face at theoverlapped portions of the horizontal projections so that the overlappedportions of the horizontal projections are exposed.
 33. A rubber crawleraccording to claim 31, wherein a rubber layer covers the overlappedportions of the horizontal projections between the core bars embedded inthe rubber crawler body, the rubber layer being absent from firstportions of at least one of the grounding face and the nongrounding faceat the overlapped portions of the horizontal projections, a thinnerrubber layer covering said first portions.
 34. A rubber crawleraccording to claim 30, wherein the engaging part of each core bar isthicker than the wing portions and has a portion extending lower thanthe wing portions, the horizontal projections being positioned on theportion of the engaging port extending lower than the wing portions. 35.A rubber crawler according to claim 34, wherein a rubber layer coversthe overlapped portions of the horizontal projections between the corebars embedded in the rubber crawler body, the rubber layer beingpartially absent on at least one of the grounding face and thenongrounding face at the overlapped portions of the horizontalprojections so that the overlapped portions of the horizontalprojections are exposed.
 36. A rubber crawler according to claim 34,wherein long slender concave grooves are provided on at least one of agrounding face and a nongrounding face of the rubber crawler laterallyoutside the overlapped portions of the horizontal projections betweenthe core bars embedded in the rubber crawler body, and said concavegrooves extend along portions of the rubber crawler in thecircumferential direction.
 37. A rubber crawler according to claim 34,wherein a rubber layer covers the overlapped portions of the horizontalprojections between the core bars embedded in the rubber crawler body,the rubber layer being absent from first portions of at least one of thegrounding face and the nongrounding face at the overlapped portions ofthe horizontal projections, a thinner rubber layer covering said firstportions.
 38. A rubber crawler according to claim 36, wherein a rubberlayer covers the overlapped portions of the horizontal projectionsbetween the core bars embedded in the rubber crawler body, the rubberlayer being partially absent on at least one of the grounding face andthe nongrounding face at the overlapped portions of the horizontalprojections so that the overlapped portions of the horizontalprojections are exposed.
 39. A rubber crawler according to claim 36,wherein a rubber layer covers the overlapped portions of the horizontalprojections between the core bars embedded in the rubber crawler body,the rubber layer being absent from first portions of at least one of thegrounding face and the nongrounding face at the overlapped portions ofthe horizontal projections, a thinner rubber layer covering said firstportions.
 40. A rubber crawler according to claim 30, wherein a rubberlayer covers the overlapped portions of the horizontal projectionsbetween the core bars embedded in the rubber crawler body, the rubberlayer being partially absent on at least one of the grounding face andthe nongrounding face at the overlapped portions of the horizontalprojections so that the overlapped portions of the horizontalprojections are exposed.
 41. A rubber crawler according to claim 30,wherein a rubber layer covers the overlapped portions of the horizontalprojections between the core bars embedded in the rubber crawler body,the rubber layer being absent from first portions of at least one of thegrounding face and the nongrounding face at the overlapped portions ofthe horizontal projections, a thinner rubber layer covering said firstportions.
 42. A rubber crawler according to claim 1, wherein theengaging part of each core bar is thicker than the wing portions and hasa portion extending lower than the wing portions, the horizontalprojections being positioned on the portion of the engaging portextending lower than the wing portions.
 43. A rubber crawler accordingto claim 42, wherein long slender concave grooves are provided on atleast one of a grounding face and a nongrounding face of the rubbercrawler laterally outside the overlapped portions of the horizontalprojections between the core bars embedded in the rubber crawler body,and said concave grooves extend along portions of the rubber crawler inthe circumferential direction.
 44. A rubber crawler according to claim43, wherein a rubber layer covers the overlapped portions of thehorizontal projections between the core bars embedded in the rubbercrawler body, the rubber layer being partially absent on at least one ofthe grounding face and the nongrounding face at the overlapped portionsof the horizontal projections so that the overlapped portions of thehorizontal projections are exposed.
 45. A rubber crawler according toclaim 43, wherein a rubber layer covers the overlapped portions of thehorizontal projections between the core bars embedded in the rubbercrawler body, the rubber layer being absent from first portions of atleast one of the grounding face and the nongrounding face at theoverlapped portions of the horizontal projections, a thinner rubberlayer covering said first portions.
 46. A rubber crawler according toclaim 42, wherein a rubber layer covers the overlapped portions of thehorizontal projections between the core bars embedded in the rubbercrawler body, the rubber layer being partially absent on at least one ofthe grounding face and the nongrounding face at the overlapped portionsof the horizontal projections so that the overlapped portions of thehorizontal projections are exposed.
 47. A rubber crawler according toclaim 42, wherein a rubber layer covers the overlapped portions of thehorizontal projections between the core bars embedded in the rubbercrawler body, the rubber layer being absent from first portions of atleast one of the grounding face and the nongrounding face at theoverlapped portions of the horizontal projections, a thinner rubberlayer covering said first portions.
 48. A rubber crawler according toclaim 1, wherein a rubber layer covers the overlapped portions of thehorizontal projections between the core bars embedded in the rubbercrawler body, the rubber layer being absent from first portions of atleast one of the grounding face and the nongrounding face at theoverlapped portions of the horizontal projections, a thinner rubberlayer covering said first portions.